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Free Radical Biology & Medicine May 2012Autism spectrum disorders (ASDs) are rarely diagnosed in children younger than 2 years, because diagnosis is based entirely on behavioral tests. Oxidative damage may... (Meta-Analysis)
Meta-Analysis Review
Autism spectrum disorders (ASDs) are rarely diagnosed in children younger than 2 years, because diagnosis is based entirely on behavioral tests. Oxidative damage may play a central role in this pathogenesis, together with the interconnected transmethylation cycle and transsulfuration pathway. In an attempt to clarify and quantify the relationship between oxidative stress-related blood biomarkers and ASDs, a systematic literature review was carried out. For each identified study, mean biomarker levels were compared in cases and controls providing a point estimate, the mean ratio, for each biomarker. After meta-analysis, the ASD patients showed decreased blood levels of reduced glutathione (27%), glutathione peroxidase (18%), methionine (13%), and cysteine (14%) and increased concentrations of oxidized glutathione (45%) relative to controls, whereas superoxide dismutase, homocysteine, and cystathionine showed no association with ASDs. For the C677T allele in the methylene tetrahydrofolate reductase gene (MTHFR), homozygous mutant subjects (TT) showed a meta-OR of 2.26 (95% CI 1.30-3.91) of being affected by ASD with respect to the homozygous nonmutant (CC). Case-control studies on blood levels of vitamins suggest a lack of association (folic acid and vitamin B12) or rare association (vitamins A, B6, C, D, E). Sparse results were available for other biomarkers (ceruloplasmin, catalase, cysteinylglycine, thiobarbituric acid-reactive substances, nitric oxide) and for polymorphisms in other genes. Existing evidence is heterogeneous and many studies are limited by small sample size and effects. In conclusion, existing evidence suggests a role for glutathione metabolism, the transmethylation cycle, and the transsulfuration pathway, although these findings should be interpreted with caution, and larger, more standardized studies are warranted.
Topics: Biomarkers; Child; Child Development Disorders, Pervasive; Child, Preschool; Glutathione; Humans; Methylenetetrahydrofolate Reductase (NADPH2); Oxidative Stress; Vitamins
PubMed: 22542447
DOI: 10.1016/j.freeradbiomed.2012.03.011 -
Journal of Ophthalmology 2019To systematically evaluate the associations between oxidative stress status and different types of glaucoma. (Review)
Review
PURPOSE
To systematically evaluate the associations between oxidative stress status and different types of glaucoma.
DESIGN
Systematic review and meta-analysis.
METHODS
We searched PubMed, EMBASE, and the Web of Science for randomized controlled trials written in the English language between January 1, 1990, and November 30, 2016. A random effects model was used to estimate oxidative stress status along with weighted mean differences and 95% confidence intervals (CIs). A funnel plot analysis and Egger's test were performed to assess potential publication bias.
MAIN OUTCOME MEASURES
Oxidative stress status was abnormal and different in patients with OAG (open-angle glaucoma) and EXG (exfoliation glaucoma).
RESULTS
Blood TAS (total antioxidant status) was lower in the OAG group than in the control group, with a mean difference of 0.580 mmol/L ( < 0.0001, 95% CI = -0.668 to -0.492). The aqueous humor SOD (superoxide dismutase), GPX (glutathione peroxidase), and CAT (catalase) levels were higher in the OAG group than in the control group, with mean differences of 17.989 U/mL ( < 0.0001, 95% CI = 14.579-21.298), 12.441 U/mL ( < 0.0001, 95% CI = 10.423-14.459), and 1.229 fmol/mL (=0.042, 95% CI = 0.043-2.414), respectively. Blood TAS was lower in the EXG group than in the control group, with a mean difference of 0.262 mmol/L ( < 0.0001, 95% CI = -0.393 to -0.132). However, there were no differences in blood TOS and aqueous humor TOS between the EXG group and the control group.
CONCLUSIONS
This meta-analysis indicates that OAG patients had a lower TAS in the blood and higher levels of SOD, GPX, and CAT in the aqueous humor, while EXG patients only had a decreased TAS in the blood.
PubMed: 30766729
DOI: 10.1155/2019/1803619 -
Placenta Feb 2023Studies about oxidative stress biomarkers revealed different phenotypes between early and late preeclampsia (PE). Despite that, there is extensive evidence of oxidative... (Meta-Analysis)
Meta-Analysis Review
Studies about oxidative stress biomarkers revealed different phenotypes between early and late preeclampsia (PE). Despite that, there is extensive evidence of oxidative stress in investigations that combinate forms different of preeclampsia. This study reviews the oxidative stress profile in the PE subtypes and evaluates which markers are altered in the blood and placental tissue. A search was conducted in databases such as MEDLINE, EMBASE, LILACS, and Web of Science without restricting the year and language of publication. The quality of the studies was evaluated by the Newcastle-Ottawa scale and Joanna Briggs Institute for analytical Cross-Sectional Studies. After 13,319 screened records, 65 were included in the systematic review. The markers of stress oxidative of damage and reactive species were those selected, such as malondialdehyde (MDA), lipid peroxide, advanced protein oxidation products, carbonyl protein, 8-hydroxy-2'-deoxyguanosine, total oxidant status, hydrogen peroxide, nitric oxide (NO). We described the antioxidant activity, including the superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase, free glutathione, and total antioxidant capacity (TAC). We results demonstrated that oxidative stress is related to pathophysiology of PE, there were increased lipid peroxidation in the blood and placenta, and in blood a reduction of NO levels and of TAC, like lower enzymatic activity of GPx, CAT in PE, and SOD in mild PE. In addition, altered levels of MDA in the placenta and blood show that placental changes have repercussions on the clinical syndrome and are related to the severity of the disease.
Topics: Humans; Female; Pregnancy; Pre-Eclampsia; Cross-Sectional Studies; Placenta; Oxidative Stress; Antioxidants; Catalase; Glutathione; Superoxide Dismutase; Glutathione Peroxidase; Nitric Oxide; Malondialdehyde
PubMed: 36669343
DOI: 10.1016/j.placenta.2022.12.009 -
Scientific Reports Aug 2023The primary antioxidant, glutathione peroxidase (GPx), is hypothesized to contribute to the pathophysiology of malaria. This current study conducted a meta-analysis to... (Meta-Analysis)
Meta-Analysis
The primary antioxidant, glutathione peroxidase (GPx), is hypothesized to contribute to the pathophysiology of malaria. This current study conducted a meta-analysis to examine variations in GPx blood levels in malaria patients. Seven electronic databases-ProQuest, Scopus, Embase, MEDLINE, PubMed, Ovid, and Google Scholar-were searched for relevant studies with no limitations to publication language or publication date. The Joanna Briggs Institute critical appraisal tools were used to appraise the risk of bias among the included studies critically. The meta-analysis was conducted by pooling the effect estimates and Hedges's g using a random-effects model. Search results returned 1253 articles, of which 16 studies were used for syntheses. Results of the meta-analysis indicated that malaria patients had decreased blood levels of GPx compared to uninfected individuals (P < 0.01, Hedges' g: - 4.06, 95% CI - 5.49-(- 2.63), I: 99.07%, 1278 malaria patients/627 uninfected individuals, 15 studies). Subgroup analyses indicated that peripheral levels of GPx were significantly diminished in patients with P. falciparum malaria compared to uninfected controls (P < 0.01, Hedges' g: - 3.06, 95% CI - 4.46-(- 1.65), I: 98.39%, 9 studies) but not in patients with P. vivax malaria (P = 0.15, Hedges' g: - 2.05, 95% CI - 4.83-0.74), I: 98.64%, 2 studies) Overall, malaria is associated with declined levels of GPx, particularly in patients with P. falciparum malaria. The finding provides valuable insights that prompt the need to investigate the role of GPx depletion in malaria pathogenesis.
Topics: Humans; Academies and Institutes; Glutathione Peroxidase; Malaria; Malaria, Falciparum; Malaria, Vivax
PubMed: 37626133
DOI: 10.1038/s41598-023-41056-x -
Antioxidants (Basel, Switzerland) Feb 2022Tree nuts, including Brazil nuts, have been hypothesized to impact cardiovascular health through the modulation of oxidative stress and inflammation. Nonetheless, a... (Review)
Review
Effect of Brazil Nuts on Selenium Status, Blood Lipids, and Biomarkers of Oxidative Stress and Inflammation: A Systematic Review and Meta-Analysis of Randomized Clinical Trials.
Tree nuts, including Brazil nuts, have been hypothesized to impact cardiovascular health through the modulation of oxidative stress and inflammation. Nonetheless, a quantitative analysis of these effects has not been performed. Therefore, the aim of this study was to systematically revise and quantify the effect of Brazil nut intervention on selenium status, blood lipids, and biomarkers of oxidative stress and inflammation using a meta-analytical approach. To meet the goals of this study, a systematic search of PubMed, EMBASE, and Web of Science databases of published randomised clinical trials reporting on dietary interventions with Brazil nuts and their effects on selenium status, blood lipids, and markers of oxidative stress and inflammation was performed. Eight articles were included for systematic review and meta-analysis. Based on the conducted analysis, a significant positive effect of Brazil nuts on selenium blood concentration (SMD = 6.93, 95% CI: 3.99; 9.87) was found. Additionally, a positive effect of Brazil nut intervention on glutathione peroxidase activity (SMD = 0.53, 95% CI: 0.07; 0.99) was observed. However, no significant results were found when considering blood lipid levels, including results for total cholesterol (SMD = -0.22, 95% CI: -0.57; 0.14), HDL cholesterol (SMD = -0.04, 95% CI: -0.28; 0.19) and LDL cholesterol (SMD = -0.15; 95% CI: -0.43; 0.13). In conclusion, the findings from this study suggest that Brazil nut consumption improves selenium status and exerts antioxidant effects, which could be considered a potential pathway for the prevention of metabolic disorders related to altered blood lipid profiles. However, further studies are needed to elucidate the effect of Brazil nuts toward blood lipid profile, also preferably controlling for other biomarkers.
PubMed: 35204285
DOI: 10.3390/antiox11020403 -
Journal of Trace Elements in Medicine... Jul 2017Available studies in the literature on the selenium levels in Alzheimer's disease (AD) are inconsistent with some studies reporting its decrease in the circulation,... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Available studies in the literature on the selenium levels in Alzheimer's disease (AD) are inconsistent with some studies reporting its decrease in the circulation, while others reported an increase or no change as compared to controls.
AIM
The objective of this study was to perform a meta-analysis of circulatory (plasma/serum and blood), erythrocyte and cerebrospinal fluid (CSF) selenium levels in AD compared controls. We also performed a meta-analysis of the correlation coefficients (r) to demonstrate the associations between selenium and glutathione peroxidase (GPx) in AD patients.
METHODS
All major databases were searched for eligible studies. We included 12 case-control/observational studies reporting selenium concentrations in AD and controls. Pooled-overall effect size as standardized mean difference (SMD) and pooled r-values were generated using Review Manager 5.3 and MedCalc 15.8 software.
RESULTS
Random-effects meta-analysis indicated a decrease in circulatory (SMD=-0.44), erythrocellular (SMD=-0.52) and CSF (SMD=-0.14) selenium levels in AD patients compared to controls. Stratified meta-analysis demonstrated that the selenium levels were decreased in both the subgroups with (SMD=-0.55) and without (SMD=-0.37) age matching between AD and controls. Our results also demonstrated a direct association between decreased selenium levels and GPx in AD.
CONCLUSION
This meta-analysis suggests that circulatory selenium concentration is significantly lower in AD patients compared to controls and this decrease in selenium is directly correlated with an important antioxidant enzyme, the GPx, in AD.
Topics: Aged; Alzheimer Disease; Erythrocytes; Female; Glutathione Peroxidase; Humans; Male; Publication Bias; Regression Analysis; Selenium
PubMed: 28595794
DOI: 10.1016/j.jtemb.2017.04.005 -
Disease Markers 2016Numerous studies suggested that oxidative stress (OS) played a central role in the onset and development of postmenopausal osteoporosis (PO); however, conflicting... (Meta-Analysis)
Meta-Analysis Review
Numerous studies suggested that oxidative stress (OS) played a central role in the onset and development of postmenopausal osteoporosis (PO); however, conflicting results were obtained as to the association of OS-related biomarkers and PO. This meta-analysis aimed to identify the association between these markers and PO, and explore factors that may explain the inconsistencies in these results. A systematic literature search was conducted in relevant database. Search terms and selection criteria were priorly determined to identify and include all studies that detected markers of OS in PO patients. We pooled data with a random effects meta-analysis with standardized mean differences and 95% confidence interval. Total 17 studies including 12 OS markers were adopted. The results showed that superoxide dismutase (SOD) in erythrocytes, catalase (CAT), total antioxidant status (TAS), hydroperoxides (HY), advanced oxidation protein products (AOPP), malondialdehyde (MDA), and vitamin B12 (VB12) in plasma/serum were not statistically different between the PO and control group, whereas significantly increased level of homocysteine (Hcy) and nitric oxide (NO), along with decreased SOD, glutathione peroxidase (GPx), folate, and total antioxidant power (TAP) in plasma/serum were obtained in the PO group. In summary, OS might serve as potential biomarkers in the etiopathophysiology and clinical course of PO.
Topics: Biomarkers; Female; Humans; Osteoporosis, Postmenopausal; Oxidative Stress
PubMed: 27594735
DOI: 10.1155/2016/7067984 -
The Journal of Clinical Endocrinology... Jul 2012The reported risk of hypothyroidism after hemithyroidectomy shows considerable heterogeneity in literature. (Meta-Analysis)
Meta-Analysis Review
CONTEXT
The reported risk of hypothyroidism after hemithyroidectomy shows considerable heterogeneity in literature.
OBJECTIVE
The aim of this systematic review and meta-analysis was to determine the overall risk of hypothyroidism, both clinical and subclinical, after hemithyroidectomy. Furthermore, we aimed to identify risk factors for postoperative hypothyroidism.
DATA SOURCES
A systematic literature search was performed using several databases, including PubMed.
STUDY SELECTION
Original articles in which an incidence or prevalence of hypothyroidism after primary hemithyroidectomy could be extracted were included.
DATA EXTRACTION
Study identification and data extraction were performed independently by two reviewers. In case of disagreement, a third reviewer was consulted.
DATA SYNTHESIS
A total of 32 studies were included in this meta-analysis. Meta-analysis was performed using logistic regression with random effect at study level. The overall risk of hypothyroidism after hemithyroidectomy was 22% (95% confidence interval, 19-27). A clear distinction between clinical (supranormal TSH levels and subnormal thyroid hormone levels) and subclinical (supranormal TSH levels and thyroid hormone levels within the normal range) hypothyroidism was provided in four studies. These studies reported on an estimated risk of 12% for subclinical hypothyroidism and 4% for clinical hypothyroidism. Positive anti-thyroid peroxidase status is a relevant preoperative indicator of hypothyroidism after surgery. Effect estimates did not differ substantially between studies with lower risk of bias and studies with higher risk of bias.
CONCLUSIONS
This meta-analysis showed that approximately one in five patients will develop hypothyroidism after hemithyroidectomy, with clinical hypothyroidism in one of 25 operated patients.
Topics: Algorithms; Humans; Hypothyroidism; Incidence; Postoperative Complications; Prognosis; Risk Factors; Thyroidectomy
PubMed: 22511795
DOI: 10.1210/jc.2012-1063 -
Foods (Basel, Switzerland) May 2022This study adopted systematic literature review and meta-analysis methodology to explored anti-oxidative effect of pu-erh tea. Study authors have systemically searched... (Review)
Review
This study adopted systematic literature review and meta-analysis methodology to explored anti-oxidative effect of pu-erh tea. Study authors have systemically searched seven databases up until 21 February 2020. In performing the literature search on the above-mentioned databases, the authors used keywords of pu-erh AND (superoxide dismutase OR glutathione peroxidase OR malondialdehyde). Results derived from meta-analyses showed statistically significant effects of pu-erh tea on reducing serum MDA levels (SMD, −4.19; 95% CI, −5.22 to −3.15; p < 0.001; I2 = 93.67%); increasing serum SOD levels (SMD, 2.41; 95% CI, 1.61 to 3.20; p < 0.001; I2 = 91.36%); and increasing serum GSH-Px levels (SMD, 4.23; 95% CI, 3.10 to 5.36; p < 0.001; I2 = 93.69%). Results from systematic review and meta-analyses validated that various ingredients found in pu-erh tea extracts had anti-oxidation effects, a long-held conventional wisdom with limited supporting evidence.
PubMed: 35564056
DOI: 10.3390/foods11091333 -
Tumour Biology : the Journal of the... Jan 2014Reactive oxygen species-related damage plays a critical role in carcinogenesis. Glutathione peroxidase 1 (GPX1) and mitochondrial superoxide dismutase (MnSOD) are two... (Meta-Analysis)
Meta-Analysis Review
Reactive oxygen species-related damage plays a critical role in carcinogenesis. Glutathione peroxidase 1 (GPX1) and mitochondrial superoxide dismutase (MnSOD) are two key antioxidant enzymes in the defense system against reactive oxygen species. This systematic review and meta-analysis was designed to evaluate the association of single-nucleotide polymorphisms in GPX1 and MnSOD genes with susceptibility to bladder cancer risk. Online databases of PubMed, Embase, China National Knowledge Infrastructure, and SinoMed were searched to identify eligible studies. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated to estimated the association strength. The fixed effects model and random effects model were used to pool the data from different studies. By pooling all eligible studies, we found that the GPX1 Pro198Leu polymorphism was associated with a significantly increased risk of bladder cancer (Leu vs. Pro, OR = 2.111, 95% CI = 1.020-4.368, heterogeneity (p < 0.001); LeuPro/LeuLeu vs. ProPro, OR = 1.876, 95% CI = 1.011-3.480, heterogeneity (p < 0.001)). No significant association of MnSOD Ala-9Val polymorphism with cancer risk was observed (AlaVal/ValVal vs. AlaAla, OR = 0.966, 95% CI = 0.754-1.239, heterogeneity (p = 0.390); Vla vs. Ala, OR = 1.038, 95% CI = 0.782-1.377, heterogeneity (p = 0.015)). This systematic review and meta-analysis demonstrated that the GPX1 Pro198Leu polymorphism significantly increased susceptibility to bladder cancer, while the MnSOD Ala-9Val polymorphism was not associated with bladder cancer risk.
Topics: Alleles; Case-Control Studies; Codon; Genetic Predisposition to Disease; Glutathione Peroxidase; Humans; Odds Ratio; Polymorphism, Single Nucleotide; Superoxide Dismutase; Urinary Bladder Neoplasms; Glutathione Peroxidase GPX1
PubMed: 24037914
DOI: 10.1007/s13277-013-1103-6